The present invention is directed to the field of biocompatible matrices for human implantation. More particularly, the present invention is directed to an intermediate composition for forming an allogeneic biocompatible matrix that is capable of carrying other implantable materials or that can be formed into a plurality of tissue implants having different properties and different shapes. The present invention is useful because it provides an intermediate composition that is versatile in its ability to be formulated into a variety of implants or grafts that are useful in the treatment of a variety of medical conditions in patients. In another aspect, the present invention is directed to the implant/graft that is formed from the intermediate composition of the present invention.
In the field of biomedical implants, devices have been made that range far afield from the biological components found in the human body. For example, many devices that are intended as bone substitutes are made from metals such as titanium, or biocompatible ceramics. A problem in such instances is that they have different material properties than the host tissue causing the devices to loosen at the interface between the host tissue and the device itself.
One solution to the problem was the use of allograft bone in place of metal or ceramic implants. Under the proper conditions and under the influence of osteogenic substances, implants made of allograft bone can act as the scaffolding for remodeling by the host. Such implants function by being both structurally and biologically similar to the host tissue. Further, they allow cellular recruitment through the natural openings in the matrix and allow the graft to be replaced by natural host bone. While allograft bone is very useful, it is limited by the intended clinical use. Thus, it is particularly useful for spinal fusions where the spacings between the vertebrae are relatively fixed and well known. However, injuries come in a variety of shapes and sizes which presents a logical limitation on the availability of an ideal graft to fill the defect. Moreover, availability, donor demographics and cost further limit the usefulness of allograft bone. Accordingly, there is a need in the art for an implantable biocompatible matrix that can be formulated into a variety of shapes and sizes and that can act as scaffolding to allow the infiltration of native regenerative cells that will lay down a natural replacement structure in the shape of the implant.
Another example area where biocompatible implants are important is in replacement skin for burn victims. Histocompatibility, remodeling and safety are considerable problems in utilizing allograft skin. To avoid this problem and the shortage of viable donor skin, a surgeon often removes skin from another part of the patient and transplants it to the area of need. While such skin is non-antigenic, it causes significant morbidity to the patient at the site of removal. Moreover, depending upon the size of the wound or burn, there may not be sufficient skin on the patient to satisfy the need. To alleviate this problem, at least one company will culture the patient's skin cells on a collagen matrix to form a transplantable layer of skin. However, the culture time is relatively extensive and the patient's wound or burn is exposed while awaiting the graft. Moreover, the grafts generated in this way do not mimic normal skin, which is composed of multiple cell types and structures. Accordingly, there is a need in the art for an implantable biocompatible matrix that can be formulated into a sheet and cut to size and that can act as scaffolding to allow the infiltration of a variety skin cells from adjacent tissue that will lay down a compatible and natural replacement structure in the shape of the implant, while absorbing the implant itself.
The present invention describes the preparation of a matrix from biological tissue that has the ability to be formulated into a variety of forms and shapes that can participate in the correction of a variety of pathologies such as those described above.